Slip Condition Investigation in Textured Surfaces with Transient Elastohydrodynamic Lubrication

The no-slip condition is an accepted condition in common fluid dynamics applications. In some cases, when high speed and pressure occur in a flow region near the surface, such as the lubrication of non-conformal surfaces, this assumption becomes controversial and the observation shows that the fluid can slide on the surfaces. This study has numerically investigated the effect of fluid slippage on the textured surface in transient elastohydrodynamic lubrication. The finite difference method extracted and discretized a numerical transient model based on the Newtonian lubricant fluid flow equations. The flow is assumed isothermal for a geometry including an upper cylinder and a lower flat dimple textured surface. A newly developed precise transient model is used for lubricated contact of a dimpled flat surface and a cylinder. This model considers passing the cylinder over a dimple in several time steps. In this paper, the model is comprehended by the critical shear stress model to consider boundary sliding. The results showed that with slippage, the lubrication friction decreases compared to the no-slip condition estimations. The occurrence of slip causes an average 15.42% decrease in the friction coefficient for flat surfaces. For dimpled surfaces, the occurrence of sliding for different depths of dimples is on average 15% decrease in the amount of friction coefficient while it decreases about 12% for different radii of the dimple.